How do you avoid biofouling on your ion exchange resins?
In water softening applications, ion exchange resins are put through extreme variations in pH during the regeneration process that normally inhibits biofouling. Most problems with biofouling occur because of improper operation or inadequate storage measures.
Biofouling refers to the damage (i.e., disintegration, cracks, etc.) of resins due to biogrowth. Biofouling can be confirmed when disinfection is no longer effective. At that point, the resins will need to be replaced after total disinfection of the tanks and pipes.
If your ion exchange system is going to be subjected to extended periods of inactivity, certain conditions should be met to minimize the potential for biological fouling. Dormant systems should be stored in a biostatic sodium chloride solution.
When shutting down the plant, ensure that the resins are in their fully exhausted form. A thorough backwash should eliminate suspended contaminants that could seed biogrowth. Fill the system until all air is evacuated from the column to ensure complete exposure to the NaCl solution. Upon restarting the system, the resins should be regenerated multiple times to make certain equilibrium is reached before normal operation is resumed.
Have you encountered biofouling in your ion exchange system? How did you deal with the problem, and what steps did you take to prevent reoccurrence?